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A Solar Energy System by Effective Sun Tracking System
SANTHIRAM ENGINEERING COLLEGE
NANDYAL_518501
KURNOOL (DT)
Presented by
T.GURUBHASKAR
3/4.E.E.E
Ph. no: 9491417285
M.Jithendra
3/4 E.E.E
Ph.no:9700717030
ABSTRACT
Electric power is the major aspect for a human
being. Without electric power there is no world.
Electric power can be generated by many ways like
coal, water, nuclear etc. Generation of power from
non-conventional energy sources improves the
system efficiency, reliability and reduces pollution.
One of such non-conventional energy source is
SOLAR ENERGY which is a complete pollution
free. A solar panel is a device that converts the
energy of sunlight directly into electricity by the
photovoltaic effect. In our project we are
generating power from sun by effective sun
tracking system means we utilize the maximum
radiation from sun by following the sun’s elevation
throughout the day using solar plates. A battery is
connected to the solar plant to store the generated
electric power. This power is utilized for the
domestic applications. Solar panel is connected to
Microcontroller through AT89S52 for controlling
panel such that it follows sun direction.
I. INTRODUCTION
Most of the electricity in India comes from
fossil-fuels like coal, oil and natural gas. Today the
demand of electricity in India is increasing and is
already more than the production of
electricity where as the reserves of the fossil-fuel
are depleting every day. We can feel this fact from
the electricity-cuts during summer. Luckily Sun
throws so much energy over India, that if we can
trap few minutes of solar energy falling over India
we can provide India with electricity for whole
year. Most parts of India get 7 KWH/ sq.-meter of
energy per day averaged over a year.
The main aim of this project is to generate
the maximum power from solar panel by
continuously tracking the sun rays.
The purpose of the project is to implement a system
to continuously track the sun rays with the help of
the solar panel and grasping the maximum power
from the sun by rotating the solar panel according
to the sun rays direction with respect to time.
In present situation everyone is facing the
problem with power cuts which is creating very
much trouble to the people. So, to solve this
problem we have a solution that is sun. Yes by
using sun radiation we can get power i.e., the solar
energy using which we generate the power. All we
are know that there are so many renewable energy
sources like solar, wind, geothermal etc. but solar
energy system is very simple and easy to
implement. But the main drawback of the solar
system is it is very poor efficient system. By using
this project we are going to improve the efficiency
of solar system.
In which solar panel will turn according to
the sun rotation with predefined angle. So by using
DC motor we are going to turn the panel according
to the time. Whenever the radiation of the sun falls
on the solar panel it grasps the radiation and stores
in it and it will send the message to the controller
about its power which is stored in it.
Microcontroller will receive this information and
display on LCD. As the time passes the panel
rotates with the help of motor. Here RTC (Real
Time Clock) is used to give the exact time intervals
to the controller.
Solar Panels are a form of active solar
power, a term that describes how solar panels make
use of the sun's energy: solar panels harvest
sunlight and actively convert it to electricity. Solar
Cells, or photovoltaic cells, are arranged in a grid-
like pattern on the surface of the solar panel. Solar
panels are typically constructed with crystalline
silicon, which is used in other industries (such as
the microprocessor industry), and the more
expensive gallium arsenide, which is produced
exclusively for use in photovoltaic (solar) cells.
Solar panels collect solar radiation from
the sun and actively convert that energy to
electricity. Solar panels are comprised of several
individual solar cells. These solar cells function
similarly to large semiconductors and utilize a
large-area p-n junction diode. When the solar cells
are exposed to sunlight, the p-n junction diodes
convert the energy from sunlight into usable
electrical energy. The energy generated from
photons striking the surface of the solar panel
allows electrons to be knocked out of their orbits
and released, and electric fields in the solar cells
pull these free electrons in a directional current,
from which metal contacts in the solar cell can
generate electricity. The more solar cells in a solar
panel and the higher the quality of the solar cells,
the more total electrical output the solar panel can
produce. The conversion of sunlight to usable
electrical energy has been dubbed the Photovoltaic
Effect.
BLOCK DIAGRAM
Fig2.1: Block diagram
2.1 BLOCK DIAGRAM EXPLANATION
MICROCONTROLLER:
The microcontroller is the heart of the
proposed embedded system. The controller used is
a low power, cost efficient chip manufactured by
ATMEL having 8K bytes of on-chip flash memory.
Microcontroller will receive this information and
display on LCD.
POWER SUPPLY:
A device or system that supplies electrical
or other types of energy to an output load or group
of loads is called a power supply unit or PSU. The
term is most commonly applied to electrical energy
supplies, less often to mechanical ones, and rarely
to others. Here we giving 5v to the micro
controller.
LCD:
Used as real time display, to know the status of the
speed of the DC motor.
H-BRIDGE:
As the time passes the panel rotates with
the help of motor. It is a driver circuit to operate the
motor.
RTC (REAL TIME CLOCK):
Here RTC (Real Time Clock) is used to
give the exact time intervals to the controller.
SOLAR PANELS:
Solar panels collect solar radiation from the sun
and actively convert that energy to electricity.
DC MOTOR:
By using DC motor we are going to turn the panel
according to the time. Whenever the radiation of
the sun falls on the solar panel it grasps the
radiation and stores in it and it will send the
message to the controller about its power which is
stored in it.
II. HARDWARE COMPONENTS
3.1POWER SUPPLY:
Fig3.1: Block diagram of power supply
Power supply is a reference to a source of electrical
power. A device or system that supplies electrical
or other types of energy to an output load or group
of loads is called a power supply unit or PSU. The
term is most commonly applied to electrical energy
supplies, less often to mechanical ones, and rarely
to others.
This power supply section is required to convert
AC signal to DC signal and also to reduce the
amplitude of the signal. The available voltage
signal from the mains is 230V/50Hz which is an
AC voltage, but the required is DC voltage (no
frequency) with the amplitude of +5V and +12V
for various applications.
In this section we have Transformer, Bridge
rectifier, are connected serially and voltage
regulators for +5V and +12V (7805 and 7812) via a
capacitor (1000µF) in parallel are connected
parallel as shown in the circuit diagram below.
Each voltage regulator output is again is connected
to the capacitors of values (100µF, 10µF, 1 µF, 0.1
µF) are connected parallel through which the
corresponding output (+5V or +12V) are taken into
consideration.
Fig3.2: Power supply diagram
Circuit Explanation
A) Transformer
A transformer is a device that transfers
electrical energy from one circuit to another
through inductively coupled electrical conductors.
A changing current in the first circuit (the primary)
creates a changing magnetic field; in turn, this
magnetic field induces a changing voltage in the
second circuit (the secondary). By adding a load to
Re
Filter
Bridge
Step
the secondary circuit, one can make current flow in
the transformer, thus transferring energy from one
circuit to the other.
The secondary induced voltage VS, of an
ideal transformer, is scaled from the primary VP by
a factor equal to the ratio of the number of turns of
wire in their respective windings:
B) Bridge Rectifier
A diode bridge or bridge rectifier is an arrangement
of four diodes in a bridge configuration that
provides the same polarity of output voltage for any
polarity of input voltage. When used in its most
common application, for conversion of alternating
current (AC) input into direct current (DC) output,
it is known as a bridge rectifier. A bridge rectifier
provides full-wave rectification from a two-wire
AC input, resulting in lower cost and weight as
compared to a center-tapped transformer design,
but has two diode drops rather than one, thus
exhibiting reduced efficiency over a center-tapped
design for the same output vol tage.
Basic Operation
When the input connected at the left
corner of the diamond is positive with respect to
the one connected at the right hand corner, current
flows to the right along the upper colored path to
theoutput, and returns to the input supply via the
lowerone.
Fig3.3: Bridge rectifier (+ve cycle)
When the right hand corner is positive relative to
the left hand corner, current flows along the upper
colored path and returns to the supply via the lower
colored path.
Fig 3.4: Bridge rectifier (-ve cycle)
In each case, the upper right output remains
positive with respect to the lower right one. Since
this is true whether the input is AC or DC, this
circuit not only produces DC power when supplied
with AC power: it also can provide what is
sometimes called "reverse polarity protection".
That is, it permits normal functioning when
batteries are installed backwards or DC input-
power supply wiring "has its wires crossed" (and
protects the circuitry it powers against damage that
might occur without this circuit in place).
Fig 3.5: Wave forms of rectifier
C) Output smoothing (Using Capacitor)
For many applications, especially with
single phase AC where the full-wave bridge serves
to convert an AC input into a DC output, the
addition of a capacitor may be important because
the bridge alone supplies an output voltage of fixed
polarity but pulsating magnitude (see diagram
above).
Fig 3.6: Smoothing capacitor
The function of this capacitor, known as a
reservoir capacitor (aka smoothing capacitor) is to
lessen the variation in (or 'smooth') the rectified AC
output voltage waveform from the bridge. One
explanation of 'smoothing' is that the capacitor
provides a low impedance path to the AC
component of the output, reducing the AC voltage
across, and AC current through, the resistive load.
In less technical terms, any drop in the output
voltage and current of the bridge tends to be
cancelled by loss of charge in the capacitor.
This charge flows out as additional current
through the load. Thus the change of load current
and voltage is reduced relative to what would occur
without the capacitor. Increases of voltage
correspondingly store excess charge in the
capacitor, thus moderating the change in output
voltage / current
Output can also be smoothed using a choke and
second capacitor. The choke tends to keep the
current (rather than the voltage) more constant. Due
to the relatively high cost of an effective choke
compared to a resistor and capacitor this is not
employed in modern equipment.
D) Voltage Regulator
A voltage regulator is an electrical regulator
designed to automatically maintain a constant
voltage level.
The 78xx (also sometimes known as LM78xx)
series of devices is a family of self-contained fixed
linear voltage regulator integrated circuits. The
78xx family is a very popular choice for many
electronic circuits which require a regulated power
supply, due to their ease of use and relative
cheapness.
When specifying individual ICs within this family,
the xx is replaced with a two-digit number, which
indicates the output voltage the particular device is
designed to provide (for example, the 7805 has a 5
volt output, while the 7812 produces 12 volts). The
78xx line is positive voltage regulators, meaning
that they are designed to produce a voltage that is
positive relative to a common ground. There is a
related line of 79xx devices which are
complementary negative voltage regulators. 78xx
and 79xx ICs can be used in combination to
provide both positive and negative supply voltages
in the same circuit, if necessary.
78xx ICs have three terminals and are most
commonly found in the TO220 form factor,
although smaller surface-mount and larger TrO3
packages are also available from some
manufacturers.
These devices typically support an input
voltage which can be anywhere from a couple of
volts over the intended output voltage, up to a
maximum of 35 or 40 volts, and can typically
provide up to around 1 or 1.5 amps of current
(though smaller or larger packages may have a
lower or higher current rating).
Fig3.7: Internal block diagram of voltage regulator
3.2 MICROCONTROLLERS:
MICROPROCESSORS VS
MICROCONTROLLERS:
• Microprocessors are single-chip CPUs used in
microcomputers.
• Microcontrollers and microprocessors are
different in three main aspects: Hardware
architecture, applications, and instruction set
features.
• Hardware architecture: A microprocessor is a
single chip CPU while a microcontroller is a single
IC contains a CPU and much of remaining circuitry
of a complete computer (e.g., RAM, ROM, serial
interface, parallel interface, timer, and interrupt
handling circuit).
• Applications: Microprocessors are commonly
used as a CPU in computers while microcontrollers
are found in small, minimum component designs
performing control oriented activities.
• Microprocessor instruction sets are processing
Intensive.
• They have instructions to set and clear individual
bits and perform bit operations.
• Processing power of a microcontroller is much
less than a microprocessor.
AT89S52:
Features:
• Compatible with MCS-51 Products
• 8K Bytes of In-System Programmable (ISP) Flash
Memory
– Endurance: 1000 Write/Erase Cycles
• 4.0V to 5.5V Operating Range
• Fully Static Operation: 0 Hz to 33 MHz
• Three-level Program Memory Lock
• 256K Internal RAM
• 32 Programmable I/O Lines
• 3 16-bit Timer/Counters
• Eight Interrupt Sources
• Full Duplex UART Serial Channel
• Low-power Idle and Power-down Modes
• Interrupt Recovery from Power-down Mode
• Watchdog Timer
The AT89S52 provides the following standard
features: 8K bytes of Flash, 256 bytes of RAM, 32
I/O lines, Watchdog timer, two data pointers, three
16-bit timer/counters, full duplex serial port, on-
chip oscillator, and clock circuitry. In addition, the
AT89S52 is designed with static logic for operation
down to zero frequency and supports two software
selectable power saving modes. The Idle Mode
stops the CPU while allowing the RAM
timer/counters, serial port, and interrupt system to
continue functioning. The Power-down mode saves
the RAM contents but freezes the oscillator,
disabling all other chip functions until the next
interrupt or hardware reset.
PIN DESCRIPTION OF
MICROCONTROLLER 89S52
VCC
Supply voltage.
GND
Ground.
Port 0
Port 0 is an 8-bit open drain bi-directional I/O port.
As an output port, each pin can sink eight TTL
inputs. When 1sare written to port 0 pins, the pins
can be used as high impedance inputs. Port 0 can
also be configured to be the multiplexed low order
address/data bus during accesses to external
program and data memory. In this mode, P0 has
internal pull-ups.Port 0 also receives the code bytes
during Flash Programming and outputs the code
bytes during program verification. External pull-
ups are required during program verification
Port 1
Port 1 is an 8-bit bi-directional I/O port with
internal pull-ups. The Port 1 Output buffers can
sink/source four TTL inputs. When 1s are written
to Port 1 pins, they are pulled high by the internal
pull-ups and can be used as inputs
Port 2
Port 2 is an 8-bit bi-directional I/O port
with internal pull-ups. The Port 2 output buffers
can sink/source four TTL inputs. When 1s are
written to Port 2 pins, they are pulled high by the
internal pull-ups and can be used as inputs. Port 2
emits the high-order address byte during fetches
from external program memory and during
accesses to external data memory that uses 16-bit
addresses (MOVX @DPTR). In this application,
Port 2 uses strong internal pull-ups when emitting
1s. During accesses to external data memory that
use 8-bit addresses (MOVX @ RI), Port 2emits the
contents of the P2 Special
Function Register. Port 2 also receives the
high-order address bits and some control signals
during Flash programming and verification
Port 3
Port 3 is an 8-bit bi-directional I/O port
with internal pull-ups. The Port 3 output buffers
can sink/source four TTL inputs. When 1s are writ
1s are written to Port 3 pins, they are pulled high by
the internal pull-ups and can be used as inputs. Port
3 also serves the functions of various special
features of the AT89S52, as shown in the following
table.
Port 3 also receives some control signals for Flash
programming
And verification.
RST
Reset input. A high on this pin for two machine
cycles while the oscillator is running resets the
device.
ALE/PROG
Address Latch Enable (ALE) is an output
pulse for latching the low byte of the address
during accesses to external memory. This pin is
also the program pulse input (PROG) during Flash
programming. In normal operation, ALE is emitted
at a constant rate of1/6 the oscillator frequency and
may be used for external timing or clocking
purposes. Note, however, that one ALE pulse is
skipped during each access to external data
Memory. If desired, ALE operation can be disabled
by setting bit 0 of SFR location 8EH. With the bit
set, ALE is active only during a MOVX or MOVC
instruction. Otherwise, the pin is weakly pulled
high. Setting the ALE-disable bit has no effect if
the micro controller is in external execution mode.
PSEN
Program Store Enable (PSEN) is the read strobe to
external program memory. When the AT89S52 is
executing code from external program memory,
PSEN is activated twice each machine cycle,
except that two PSEN activations are skipped
during each access to external data memory.
EA/VPP
External Access Enable. EA must be strapped to
GND in order to enable the device to fetch code
from external program memory locations starting at
0000H up to FFFFH.Note, however, that if lock bit
1 is programmed, EA will be internally latched on
reset. A should be strapped to VCC for internal
program executions. This pin also receives the 12-
voltProgramming enables voltage (VPP) during
Flash programming.
XTAL1
Input to the inverting oscillator amplifier and input
to the internal clock operating circuit.
XTAL2
Output from the inverting oscillator amplifier.
Oscillator Characteristics
XTAL1 and XTAL2 are the input and
output, respectively, of an inverting amplifier that
can be configured for use as an on-chip oscillator,
as shown in Figure 1. Either a quartz crystal or
ceramic resonator may be used. To drive the device
from an External clock source, XTAL2 should be
left unconnected while XTAL1 is driven, as shown
in Figure
Figure 3.8: Oscillator Connections
Special Function Register (SFR) Memory:
Special Function Registers (SFR s) are areas of
memory that control specific functionality of the
8051 processor. For example, four SFRs permit
access to the 8051’s 32 input/output lines.
Another SFR allows the user to set the
serial baud rate, control and access timers, and
configure the 8051’s interrupt system.
Accumulator:
The Accumulator, as its name suggests is
used as a general register to accumulate the results
of a large number of instructions. It can hold 8-bit
(1-byte) value and is the most versatile register.
“R” registers:
The “R” registers are a set of eight
registers that are named R0, R1. Etc up to R7.
These registers are used as auxiliary registers in
many operations.
The “B” registers: The “B” register is very similar
to the accumulator in the sense that it may hold an
8-bit (1-byte) value. Two only uses the “B” register
8051 instructions: MUL AB and DIV AB.The Data
Pointer: The Data pointer (DPTR) is the 8051’s
only user accessible 16-bit (2Bytes) register. The
accumulator, “R” registers are all 1-Byte values.
DPTR, as the name suggests, is used to point to
data. It is used by a number of commands, which
allow the 8051 to access external memory.
3.3 LCD (LIQUID CRISTAL DISPLAY)
1. The declining prices of LCDs make its use cost-
effective.
2. The ability to display numbers, characters and
graphics. This is contrast to LEDs, which has
limited to numbers and few characters.
Incorporation of a refreshing controller into LCD,
thereby relieving the CPU of the task of refreshing
the LCD. In contrast, the LED must be refreshed by
the CPU to keep displaying data.
3. Ease of programming for characters and
Fig 3.9: LCD pin description
LCD PIN DESCRIPTION
The LCD which we have used in our
project is a 16×2 alpha numeric LCD. It has 16
pins. Figure shows the position of various pins.
1. VCC, VSS, and VEE
While VCC and VSS provide +5V and
ground, respectively, VEE is used for controlling
LCD contrast.
2. RS (Register Select)
There are two very important registers
inside the LCD. The RS pin is used for their
selection as follows. If RS=0, the instruction
command code register is selected, allowing the
user to send a command such as clear display,
cursor at home, etc. If RS=1, the data register is
selected, allowing the user to send data to be
displayed on LCD.
3. R/W (Read/Write)
R/W input allows the user to write
information to LCD or read information from it.
R/W=1 when reading; R/W=0 when writing.
4. E (Enable)
The enable pin is used by the LCD to latch
information presented to its data pins. When data is
supplied to data pins, a high-to-low pulse must be
applied to this pin in order for the LCD to latch in
the data present the data pins. This pulse must be a
minimum of 450 ns wide.
5. D0-D7 (8-bit Data bus)
The 8-bit data pins, D0-D7, are used to
send information to the LCD or read the contents of
the LCD’s internal registers. To display letters and
numbers, we send ASCII codes for the letters A-Z,
a-z, and numbers 0-9 to these pins while making
6. RS=1
There are also instruction command codes
that can be sent to LCD to clear the cursor to the
home position or blink the cursor. Table lists some
of the instruction command codes.
Code Command to LCD Instruction Register (Hex)
1 Clear Display screen
2 Return home
4 Shift cursor left
6 Shift cursor right
5 Shift Display right
7 Shift Display left
8 Display off, cursor off
A Display off, cursor on
C Display on, cursor off
E Display on, cursor blinking
F Display on, cursor blinking
80 Force cursor to beginning of 1st line
C0 Force cursor to beginning of 2nd line
3.4 DC MOTOR:
A DC motor is designed to run on DC
electric power. Two examples of pure DC designs
are Michael Faraday's homopolar motor (which is
uncommon), and the ball bearing motor, which is
(so far) a novelty. By far the most common DC
motor types are the brushed and brushless types,
which use internal and external commutation
respectively to create an oscillating AC current
from the DC source -- so they are not purely DC
machines in a strict sense.
Fig3.10: DC Motor
Types of dc motors:
1. Brushed DC Motors
2. Brushless DC motors
3. Coreless DC motors
4. Brushed DC motors:
The classic DC motor design generates an
oscillating current in a wound rotor with a split
ring commutator, and either a wound or
permanent magnet stator. A rotor consists of a
coil wound around a rotor which is then
powered by any type of battery.Many of the
limitations of the classic commutator DC
motor are due to the need for brushes to press
against the commutator. This creates friction.
At higher speeds, brushes have increasing
difficulty in maintaining contact. Brushes may
bounce off the irregularities in the commutator
surface, creating sparks. This limits the
maximum speed of the machine. The current
density per unit area of the brushes limits the
output of the motor. The imperfect electric
contact also causes electrical noise. Brushes
eventually wear out and require replacement,
and the commutator itself is subject to wear
and maintenance.
Brushless DC motors:
Some of the problems of the brushed DC
motor are eliminated in the brushless design. In this
motor, the mechanical "rotating switch" or
commutator/brush gear assembly is replaced by an
external electronic switch synchronized to the
rotor's position. Brushless motors are typically 85-
90% efficient, whereas DC motors with brush gear
are typically 75-80% efficient.
Midway between ordinary DC motors and stepper
motors lies the realm of the brushless DC motor.
Built in a fashion very similar to stepper motors,
these often use a permanent magnet external rotor,
three phases of driving coils, one or more Hal
effect sensors to sense the position of the rotor, and
the associated drive electronics. The coils are
activated, one phase after the other, by the drive
electronics as cued by the signals from the Hall
effect sensors. In effect, they act as three-phase
synchronous motors containing their own variable-
frequency drive electronics.
Brushless DC motors are commonly used where
precise speed control is necessary, as in computer
disk drives or in video cassette recorders, the
spindles within CD, CD-ROM (etc.) drives, and
mechanisms within office products such as fans,
laser printers and photocopiers. They have several
advantages over conventional motors:
Compared to AC fans using shaded-pole
motors, they are very efficient, running much
cooler than the equivalent AC motors. This
cool operation leads to much-improved life of
the fan's bearings.
Without a commutator to wear out, the life of a
DC brushless motor can be significantly longer
compared to a DC motor using brushes and a
commutator. Commutation also tends to cause
a great deal of electrical and RF noise; without
a commutator or brushes, a brushless motor
may be used in electrically sensitive devices
like audio equipment or computers.
The motor can be easily synchronized to an
internal or external clock, leading to precise
speed control.
Coreless DC motors:
Nothing in the design of any of the motors
described above requires that the iron (steel)
portions of the rotor actually rotate; torque is
exerted only on the windings of the electromagnets.
Taking advantage of this fact is the coreless DC
motor, a specialized form of a brush or brushless
DC motor.
Optimized for rapid acceleration, these
motors have a rotor that is constructed without any
iron core. The rotor can take the form of a winding-
filled cylinder inside the stator magnets, a basket
surrounding the stator magnets, or a flat pancake
(possibly formed on a printed wiring board)
running between upper and lower stator magnets.
These motors were commonly used to
drive the capstan(s) of magnetic tape drives and are
still widely used in high-performance servo-
controlled systems, like radio-controlled
vehicles/aircraft, humanoid robotic systems,
industrial automation, medical devices, etc.
3.5 H-BRIDGE (MOTOR DRIVER)
Fig3.11: Structure of an H-bridge (highlighted in
red)
An H-bridge is an electronic circuit which
enables a voltage to be applied across a load in
either direction. These circuits are often used in
robotics and other applications to allow DC motors
to run forwards and backwards. H-bridges are
available as integrated circuits The term "H-
bridge" is derived from the typical graphical
representation of such a circuit. An H-bridge is
built with four switches . When the switches S1 and
S4 (according to the first figure) are closed (and S2
and S3 are open) a positive voltage will be applied
across the motor. By opening S1 and S4 switches
and closing S2 and S3 switches, this voltage is
reversed, allowing reverse operation of the motor.
Operation:
Fig3.12: The two basic states of an H-bridge
The H-Bridge arrangement is generally used to
reverse the polarity of the motor, but can also be
used to 'brake' the motor, where the motor comes to
a sudden stop, as the motor's terminals are shorted,
or to let the motor 'free run' to a stop, as the motor
is effectively disconnected from the circuit. The
following table summarizes operation.
S1 S2 S3 S4 Result
1 0 0 1 Motor moves right
0 1 1 0 Motor moves left
0 0 0 0 Motor free runs
0 1 0 1 Motor brakes
1 0 1 0 Motor brakes
Construction
Fig3.13: Typical solid state H-bridge
A solid-state H-bridge is typically constructed
using reverse polarity devices (i.e., PNP BJTs or P-
channel MOSFETs connected to the high voltage
bus and NPN BJTs or N-channel MOSFETs
connected to the low voltage bus).
The most efficient MOSFET designs use N-channel
MOSFETs on both the high side and low side
because they typically have a third of the ON
resistance of P-channel MOSFETs. This requires a
more complex design since the gates of the high
side MOSFETs must be driven positive with
respect to the DC supply rail. However, many
integrated circuit MOSFET drivers include a
charge pump within the device to achieve this.
Alternatively, a switch-mode DC-DC converter can
be used to provide isolated ('floating') supplies to
the gate drive circuitry. A multiple-output fly back
converter is well-suited to this application.
A "double pole double throw" relay can generally
achieve the same electrical functionality as an H-
bridge (considering the usual function of the
device). An H-bridge would be preferable to the
relay where a smaller physical size, high speed
switching, or low driving voltage is needed, or
where the wearing out of mechanical parts is
undesirable.
3.6 REAL-TIME CLOCK
Dallas semiconductor real-time clock from
an older PC. This version also contains a battery
backed SRAM.
A real-time clock (RTC) is a computer clock
(most often in the form of an integrated circuit) that
keeps track of the current time. Although the term
often refers to the devices in personal computers,
servers and embedded systems, RTCs are present in
almost any electronic device which needs to keep
accurate time.
Terminology
The term is used to avoid confusion with
ordinary hardware clocks which are only signals
that govern digital electronics, and do not count
time in human units. RTC should not be confused
with real-time computing, which shares its three-
letter acronym, but does not directly relate to time
of day.
Purpose
Although keeping time can be done without an
RTC, using one has benefits:
Low power consumption (important when
running from alternate power)
Frees the main system for time-critical tasks
Sometimes more accurate than other methods
A GPS receiver can shorten its startup
time by comparing the current time, according to
its RTC, with the time at which it last had a valid
signal. If it has been less than a few hours then the
previous ephemeris is still usable.
Power source
RTCs often have an alternate source of
power, so they can continue to keep time while the
primary source of power is off or unavailable. This
alternate source of power is normally a lithium
battery in older systems, but some newer systems
use a supercapacitor, because they are rechargeable
and can be soldered. The alternate power source
can also supply power to battery backed RAM.
Timing
Most RTCs use a crystal oscillator, but some use
the power line frequency. In many cases the
oscillator's frequency is 32.768 kHz. This is the
same frequency used in quartz clocks and watches,
and for the same reasons, namely that the
frequency is exactly 215 cycles per second, which is
a convenient rate to use with simple binary counter
circuits.
System time
In computer science and computer
programming, system time represents a computer
system's notion of the passing of time. In this sense,
time also includes the passing of days on the
calendar.
System time is measured by a system
clock, which is typically implemented as a simple
count of the number of ticks that have transpired
since some arbitrary starting date, called the epoch.
For example, Unix and POSIX-compliant systems
encode system time as the number of seconds
elapsed since the start of the epoch at 1 January
1970 00:00:00 UT. Windows NT counts the
number of 100-nanosecond ticks since 1 January
1601 00:00:00 UT as reckoned in the proleptic
Gregorian calendar, but returns the current time to
the nearest millisecond.
UNIX date command
System time can be converted into
calendar time, which is a form more suitable for
human comprehension. For example, the Unix
system time that is 1,000,000,000 seconds since the
beginning of the epoch translates into the calendar
time 9 September 2001 01:46:40 UT. Library
subroutines that handle such conversions may also
deal with adjustments for time zones, Daylight
Saving Time (DST), leap seconds, and the user's
locale settings. Library routines are also generally
provided that convert calendar times into system
times.
Closely related to system time is process
time, which is a count of the total CPU time
consumed by an executing process. It may be split
into user and system CPU time, representing the
time spent executing user code and system kernel
code, respectively. Process times are a tally of CPU
instructions or clock cycles and generally have no
direct correlation to wall time.
File systems keep track of the times that
files are created, modified, and/or accessed by
storing timestamps in the file control block (or
inode) of each file and directory.
It should be noted that most first-generation PCs did
not keep track of dates and times. Retrieving
system time.
3.7 SOLAR PANEL
Solar panel specifications:
Solar panels use sunlight to re-charge RV
batteries. The process is called PHOTOVOLTAICS
(PV). We stock panels that have a life expectancy
of over 30 years and have a manufacturer's
warranty on output of 25 years long. We prefer the
brands that use "solid crystal silicon" cells for the
highest efficiency as they work well under adverse
conditions -- even on rainy days.
The strong aluminum frame is glazed with
special clear and toughened tempered glass that
may withstand hailstones and other hazards. We
expect these long-life panels made by SHELL, BP
SOLAR, KYOCERA/SHARP/ and others will
work for 30 years or more.
Photovoltaic module:
"Solar panel" redirects here. For the heat collectors,
see Solar thermal collector.
Fig3.14: Photovoltaic module
A photovoltaic module is composed of
individual PV cells. This crystalline-silicon module
has an aluminium frame and glass on the front.
A PV module on the ISS.
A photovoltaic module or photovoltaic
panel is a packaged interconnected assembly of
photovoltaic cells, also known as solar cells. The
photovoltaic module, known more commonly as
the solar panel, is then used as a component in a
larger photovoltaic system to offer electricity for
commercial and residential applications.
Because a single photovoltaic module can
only produce a limited amount of power, many
installations contain several modules or panels and
this is known as a photovoltaic array. A
photovoltaic installation typically includes an array
of photovoltaic modules or panels, an inverter,
batteries and interconnection wiring.
Photovoltaic systems are used for either on- or off-
grid applications, and for solar panels on
spacecraft.
Working of SOLAR panel:
Solar panels collect solar radiation from
the sun and actively convert that energy to
electricity. Solar panels are comprised of several
individual solar cells. These solar cells function
similarly to large semiconductors and utilize a
large-area p-n junction diode. When
the solar cells are exposed to sunlight, the p-n
junction diodes convert the energy from sunlight
into usable electrical energy. The energy generated
from photons striking the surface of the solar panel
allows electrons to be knocked out of their orbits
and released, and electric fields in the solar cells
pull these free electrons in a directional current,
from which metal contacts in the solar cell can
generate electricity.
The more solar cells in a solar panel and
the higher the quality of the solar cells, the more
total electrical output the solar panel can produce.
The conversion of sunlight to usable electrical
energy has been dubbed the Photovoltaic Effect.
Solar Insolation and Solar Panel Efficiency:
Solar Insolation is a measure of how much
solar radiation a given solar panel or surface
receives. The greater the insolation, the more solar
energy can be converted to electricity by the solar
panel. Click to learn more about solar insolation.
Other factors that affect the output of solar
panels are weather conditions, shade caused by
obstructions to direct sunlight, and the angle and
position at which the solar panel is installed. Solar
panels function the best when placed in direct
sunlight, away from obstructions that might cast
shade, and in areas with high regional solar
insolation ratings.
Solar panel efficiency can be optimized by
using dynamic mounts that follow the position of
the sun in the sky and rotate the solar panel to get
the maximum amount of direct exposure during the
day as possible.
Current research on materials and devices:
Developing new technologies based on
new solar cell architectural designs; and developing
new materials to serve as light absorbers and
charge carriers.
Crystalline silicon modules:
Most solar module are currently
produced from silicon PV cells. These are typically
categorized into either mono crystalline or multi
crystalline modules.
Thin-film modules:
Third generation solar cells are advanced
thin-film cells. They produce high-efficiency
conversion at low cost.
Rigid thin-film modules:
In rigid thin film modules, the cell and the
module are manufactured in the same production
line.
The cell is created directly on a glass
substrate or superstrate, and the electrical
connections are created in situ, a so called
"monolithic integration". The substrate or
superstrate is laminated with an encapsulant to a
front or back sheet, usually another sheet of glass.
The main cell technologies in this
category are CdTe, or a-Si, or a-Si+uc-Si tandem,
or CIGS (or variant). Amorphous silicon has a
sunlight conversion rate of 6-12%.
Flexible thin-film modules:
Flexible thin film cells and modules are
created on the same production line by depositing
the photoactive layer and other necessary layers on
a flexible substrate.
If the substrate is an insulator (e.g.
polyester or polyimide film) then monolithic
integration can be used.
If it is a conductor then another technique for
electrical connection must be used.
Module performance and lifetime:
Module performance is generally rated
under Standard Test Conditions (STC) : irradiance
of 1,000 W/m², solar spectrum of AM 1.5 and
module temperature at 25°C.Electrical
characteristics include nominal power (PMAX,
measured in W), open circuit voltage (VOC), short
circuit current (ISC, measured in amperes),
maximum power voltage (VMPP), maximum power
current (IMPP) and module efficiency (%).Solar
panels must withstand heat, cold, rain and hail for
many years. Many Crystalline silicon module
manufacturers offer warranties that guarantee
electrical production for 10 years at 90% of rated
power output and 25 years at 80% .
Solar cell:
A solar cell is a device that converts the
energy of sunlight directly into electricity by the
photovoltaic effect. Sometimes the term solar cell
is reserved for devices intended specifically to
capture energy from sunlight such as solar panels
and solar cells, while the term photovoltaic cell is
used when the light source is unspecified.
Assemblies of cells are used to make solar panels,
solar modules, or photovoltaic arrays.
Photovoltaics is the field of technology and
research related to the application of solar cells in
producing electricity for practical use. The energy
generated this way is an example of solar energy
(also known as solar power).
Fig3.15: Solar cell
History of solar cells:
The term "photovoltaic" comes from the
Greek φῶς (phōs) meaning "light", and "voltaic",
meaning electric, from the name of the Italian
physicist Volta, after whom a unit of electro-motive
force, the volt, is named. The term "photo-voltaic"
has been in use in English since 1849.
The photovoltaic effect was first
recognized in 1839 by French physicist A. E.
Becquerel. However, it was not until 1883 that the
first solar cell was built, by Charles Fritts, who
coated the semiconductor selenium with an
extremely thin layer of gold to form the junctions.
The device was only around 1% efficient.
Subsequently Russian physicist Aleksandr Stoletov
built the first solar cell based on the outer
photoelectric effect (discovered by Heinrich Hertz
earlier in 1887). Albert Einstein explained the
photoelectric effect in 1905 for which he received
the Nobel Prize in Physics in 1921. Russell Ohl
patented the modern junction semiconductor solar
cell in 1946, which was discovered while working
on the series of advances that would lead to the
transistor.
Simple explanation for working of solar panel:
1. Photons in sunlight hit the solar panel and are
absorbed by semiconducting materials, such as
silicon.
2. Electrons (negatively charged) are knocked
loose from their atoms, allowing them to flow
through the material to produce electricity. Due
to the special composition of solar cells, the
electrons are only allowed to move in a single
direction.
3. An array of solar cells converts solar energy
into a usable amount of direct current (DC)
electricity.
Photo generation of charge carriers:
When a photon hits a piece of silicon, one of three
things can happen:
1. The photon can pass straight through the silicon
— this (generally) happens for lower energy
photons.
2. The photon can reflect off the surface.
3. The photon can be absorbed by the silicon, if
the photon energy is higher than the silicon
band gap value. This generates an electron-hole
pair and sometimes heat, depending on the band
structure.
Charge carrier separation:
There are two main modes for charge carrier
separation in a solar cell:
1. Drift of carriers, driven by an electrostatic field
established across the device
2. Diffusion of carriers from zones of high carrier
concentration to zones of low carrier
concentration (following a gradient of
electrochemical potential).
In the widely used p-n junction solar cells,
the dominant mode of charge carrier separation is
by drift. However, in non-p-n-junction solar cells
(typical of the third generation solar cell research
such as dye and polymer solar cells), a general
electrostatic field has been confirmed to be absent,
and the dominant mode of separation is via charge
carrier diffusion.
The p-n junction:
The most commonly known solar cell is
configured as a large-area p-n junction made from
silicon. As a simplification, one can imagine
bringing a layer of n-type silicon into direct contact
with a layer of p-type silicon. In practice, p-n
junctions of silicon solar cells are not made in this
way, but rather by diffusing an n-type dopant into
one side of a p-type wafer (or vice versa).
If a piece of p-type silicon is placed in
intimate contact with a piece of n-type silicon, then
a diffusion of electrons occurs from the region of
high electron concentration (the n-type side of the
junction) into the region of low electron
concentration (p-type side of the junction). When
the electrons diffuse across the p-n junction, they
recombine with holes on the p-type side. The
diffusion of carriers does not happen indefinitely,
however, because charges build up on either side of
the junction and create an electric field. The
electric field creates a diode that promotes charge
flow, known as drift current, that opposes and
eventually balances out the diffusion of electron
and holes. This region where electrons and holes
have diffused across the junction is called the
depletion region because it no longer contains any
mobile charge carriers. It is also known as the
space charge region.
Connection to an external load:
Ohmic metal-semiconductor contacts are
made to both the n-type and p-type sides of the
solar cell, and the electrodes connected to an
external load. Electrons that are created on the n-
type side, or have been "collected" by the junction
and swept onto the n-type side, may travel through
the wire, power the load, and continue through the
wire until they reach the p-type semiconductor-
metal contact. Here, they recombine with a hole
that was either created as an electron-hole pair on
the p-type side of the solar cell, or a hole that was
swept across the junction from the n-type side after
being created there. The voltage measured is equal
to the difference in the quasi Fermi levels of the
minority carriers, i.e. electrons in the p-type portion
and holes in the n-type portion.
SOLAR CELL EFFICIENCY FACTORS:
Energy conversion efficiency:
A solar cell's energy conversion efficiency
(η, "eta"), is the percentage of power converted
(from absorbed light to electrical energy) and
collected, when a solar cell is connected to an
electrical circuit. This term is calculated using the
ratio of the maximum power point, Pm, divided by
the input light irradiance (E, in W/m2) under
standard test conditions (STC) and the surface area
of the solar cell (Ac in m2).
STC specifies a temperature of 25 °C and
an irradiance of 1000 W/m2 with an air mass 1.5
(AM1.5) spectrum. These correspond to the
irradiance and spectrum of sunlight incident on a
clear day upon a sun-facing 37°-tilted surface with
the sun at an angle of 41.81° above the horizon.
This condition approximately represents solar noon
near the spring and autumn equinoxes in the
continental United States with surface of the cell
aimed directly at the sun. Thus, under these
conditions a solar cell of 12% efficiency with a
100 cm2 (0.01 m2) surface area can be expected to
produce approximately 1.2 watts of power.
The efficiency of a solar cell may be
broken down into reflectance efficiency,
thermodynamic efficiency, charge carrier
separation efficiency and conductive efficiency.
The overall efficiency is the product of each of
these individual efficiencies.
Due to the difficulty in measuring these
parameters directly, other parameters are measured
instead: thermodynamic efficiency, quantum
efficiency, VOC ratio, and fill factor. Reflectance
losses are a portion of the quantum efficiency under
"external quantum efficiency". Recombination
losses make up a portion of the quantum efficiency,
VOC ratio, and fill factor. Resistive losses are
predominantly categorized under fill factor, but
also make up minor portions of the quantum
efficiency, VOC ratio.
Bulk technology:
These bulk technologies are often referred
to as wafer-based manufacturing. In other words, in
each of these approaches, self-supporting wafers
between 180 to 240 micrometers thick are
processed and then soldered together to form a
solar cell module.
Crystalline silicon:
Fig3.16: Basic structure of a silicon based solar cell
and its working mechanism
By far, the most prevalent bulk material
for solar cells is crystalline silicon (abbreviated as a
group as c-Si), also known as "solar grade silicon".
Bulk silicon is separated into multiple categories
according to crystallinity and crystal size in the
resulting ingot, ribbon, or wafer.
1. Mono crystalline silicon (c-Si): often made using
the Czochralski process. Single-crystal wafer cells
tend to be expensive, and because they are cut from
cylindrical ingots, do not completely cover a square
solar cell module without a substantial waste of
refined silicon. Hence most c-Si panels have
uncovered gaps at the four corners of the cells.
2. Poly or multi crystalline silicon (poly-Si or mc-Si):
made from cast square ingots — large blocks of
molten silicon carefully cooled and solidified.
Poly-Si cells are less expensive to produce than
single crystal silicon cells, but are less efficient. US
DOE data shows that there were a higher number
of multi crystalline sales than mono crystalline
silicon sales.
Ribbon silicon is a type of multi
crystalline silicon: it is formed by drawing flat thin
films from molten silicon and results in a multi
crystalline structure. These cells have lower
efficiencies than poly-Si, but save on production
costs due to a great reduction in silicon waste, as
this approach does not require sawing from ingots.
Lifespan:
Most commercially available solar cells
are capable of producing electricity for at least
twenty years without a significant decrease in
efficiency. The typical warranty given by panel
manufacturers is for a period of 25 - 30 years,
wherein the output shall not fall below 85% of the
rated capacity.
Costs:
Cost is established in cost-per-watt and in
cost-per-watt in 24 hours for infrared capable
photovoltaic cells.
SOFTWARE COMPONENTS
4.1 EMBEDDED ’C’
Software’s used are:
*Keil software for c programming
*Express PCB for lay out design
*Express SCH for schematic design
4.2 KEIL SOFTWARE
Installing the Keil software on a Windows PC
Insert the CD-ROM in your computer’s CD
drive.
On most computers, the CD will “auto run”,
and you will see the Keil installation menu. If
the menu does not appear, manually double
click on the Setup icon, in the root directory:
you will then see the Keil menu.
On the Keil menu, please select “Install
Evaluation Software”. (You will not require a
license number to install this software).
Follow the installation instructions as they
appear.
Loading the Projects
The example projects for this book are NOT loaded
automatically when you install the Keil compiler.
These files are stored on the CD in a directory
“/Pont”. The files are arranged by chapter: for
example, the project discussed in Chapter 3 is in
the directory “/Pont/Ch03_00-Hello”.
Rather than using the projects on the CD (where
changes cannot be saved), please copy the files
from CD onto an appropriate directory on your
hard disk.
Note: you will need to change the file properties
after copying: file transferred from the CD will be
‘read only’.
III. RESULT ANALYSIS
Case (i):
Fig 5.1: Panel inclination at initial
condition
At the initial condition, the panel is perpendicular
to the sunlight with ZERO inclination.
Case (ii):
Fig 5.2: Panel inclination after one hour
After one Hour duration, the sun is elevated.
According to sun direction the panel is also
elevated with inclination of 15o.
Case (iii):
Fig 5.3: Panel inclination at noon period
At the noon period, the sun’s radiation is
perpendicular to the earth surface. At this time, the
panel is parallel to earth surface i.e., perpendicular
to sun’s radiation as usual.
FUTURE ASPECTS
By using special sensors we can get exact sun
tracking instead of time based tracking system.
By preparing infrared solar panels we may generate
power even in night times and also in cloudy days.
Infrared solar panels are differing from traditional
solar panels in the glass cover of collector only.
To turn a photovoltaic solar cell into an infrared
solar energy panel the glass has to be treated during
the production phase. It is turned into low ironed
tempered glass as opposed to normal ironed
tempered glass.
By producing low ironed tempered glass, it means
that the system can absorb high wavelength
sunlight. The high wave length range is from 800 to
1200nm and this is the infrared range. A lower
wave length from 400 to 800nm is the normal
visible sunlight.
APPENDIX
Code:
#include<reg51.h>
#include<string.h>
#include “lcddisplsy.h”
#include “eeprom.h”
Sbit in1 = p2^2;
Sbit in1 = p2^3;
Sbit in1 = p2^4;
Sbit in1 = p2^5;
Sbit sw = p3^1;
Unsigned char B1 , B2 , B3 , Z ;
Unsigned char l , s , n , a , b , I , count , b2temp ,
rcount ;
Unsigned int x ;
Bit BK=0 ;
Void main()
{
b2temp=rcount=0 ;
lcd_init();
display(100);
lcd_init();
display(100);
lcdcmd(0×84);
msgdisplay(“WELCOME”);
display(1000);
lcdcmd(0×01);
msgdisplay(“SOLAR TRACKER”);
lcdcmd(0×01);
/*****start rtc chip*****
/Write_eeprom(0,0)
Display(500);
Write_eeprom(1,0);
Display(500);
Write_eeprom(1,0);
Display(500);
Msgdisplay(“ TIME:”);
While(1)
{
Xx:lcdcmd(0×c1);
For(i=3;i>0;i- -)
{
Z=read_eeprom(i-1);
B1=z&0×0f;
B2=(z&0×f0)>>4;
Lcddata(B2+0×30);
Lcddata(B1+0×30);
If(I !=1)
Lcddata( ‘ : ‘);
If(i==2)
{
If(b2temp!=z)
{
En1=1;
If(rcount<10) //rotate in clockwise
direction
{
In1=1;
In2=0;
}
Else // rotate in anticlockwise direction
{
In1=0;
In2=1;
}
rcount=rcount+1;
if(rcount==20)
rcount=0;
b2temp=z;
delay(200);
en1=0;
in1=in2=0;
}
}
For(x=0;x<1000;x++) //check for switch
{
if(sw==0) //if switch is pressed then
rotate the base
{
delay(1000);
while(sw==0);
en2=1;
in3=1;
in4=0;
delay(1000);
while(sw==1);
en2=0;
in3=0;
in4=0;
while(sw==0);
goto xx;
}
}
}
}}
CONCLUSION
By using solar energy for power generation we are
saving the conventional energy sources for future
generation to maintain balanced power generation.
In our project, we are going to replace the
traditional solar energy collection which is a costly
and very low efficiency process by using solar
tracking system connecting to the solar panel such
that the panel is always perpendicular to the sun
elevation.
It is convenient for the higher power generation.
But it also has a drawback of highly economic.
BIBLIOGRAPHY
Reference Books:
1. The 8051 Micro controller and Embedded
Systems by Muhammad Ali Mazidi,
Janice Gillispie Mazidi
2. Fundamentals of Micro processors and Micro
computers by B. Ram
3. Micro processor Architecture, Programming &
Applications by Ramesh S.
Gaonkar
4. Electrical Machines By P.S.Bimbra
5. .Non-Conventional Energy Sources by G.D.
Rai
References on the Web:
1. www.national.com
2. www.atmel.com
3. www.microsoftsearch.com
4. www.geocities.com